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c# - EF Core 未引发 ValidationException

问题描述

我有一个像这样的基DbContext类

public abstract class DbContextBase : DbContext
{
    public DbContextBase()
    {
    }

    public DbContextBase(DbContextOptions options)
        : base(options)
    {
    }

    public override int SaveChanges()
    {
        this.ValidateEntities();

        return base.SaveChanges();
    }

    public override Task<int> SaveChangesAsync(CancellationToken cancellationToken = default(CancellationToken))
    {
        this.ValidateEntities();

        return base.SaveChangesAsync(cancellationToken);
    }

     public override Task<int> SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default(CancellationToken))
     {
        this.ValidateEntities();

        return base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken);
    }

    protected virtual void ValidateEntities()
    {
        var entities = this.ChangeTracker.Entries().
                            Where(s => s.State == EntityState.Added || s.State == EntityState.Modified);

        foreach (var entity in entities)
        {
            var validationContext = new ValidationContext(entity);
            Validator.ValidateObject(entity, validationContext);
        }
    }
}

我所有的 Db Context 类都继承自这个基类。问题是即使存在验证违规，该行Validator.ValidateObject()也不会抛出。ValidationException在调试器中，我可以看到这一行已执行。例如，对于下面的模型类，我尝试SaveChangesAsync()使用Nameset to调用，null但验证通过了：

public class MyModel : IEntity<long>
{
    [Key]
    public long Id { get; set; }

    [Required]
    public string Name { get; set; }
}

IEntity<T>只是将属性强加于Id所有模型。

标签： c#asp.net-core-webapief-core-2.1model-validation

解决方案

问题是变量entity不保存实体实例，而是更改跟踪器（EntityEntry）实例，所以代码试图验证错误的东西。

所以要么重命名变量并使用entry.Entity属性：

var entries = this.ChangeTracker.Entries()
    .Where(s => s.State == EntityState.Added || s.State == EntityState.Modified);

foreach (var entry in entries)
{
    var validationContext = new ValidationContext(entry.Entity);
    Validator.ValidateObject(entry.Entity, validationContext);
}

或保持代码不变，但确保entities变量包含可枚举的实体实例：

var entities = this.ChangeTracker.Entries()
    .Where(s => s.State == EntityState.Added || s.State == EntityState.Modified)
    .Select(s => s.Entity); // <--

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